Telephone system



INVENTOR. FRA NZ ETZEL f' ATTORNE we. E9, 1939. F. ETZEL TELEPHONE SYSTEM Filed Feb. 24, 1938 2 Sheets-Sheet 2 INVENTOR, FRA/VZ ETZEL l `ATTORNE i of the highly rated call `only being scriber, then over Vpose of setting up outgoing l The attached drawings,y comprising Figs. 1

Patented Dec. 19, 1939 i nutren s'rarss TELEPHONE sr STEM Franz Etzel, Berlin-Siemensstadt, Germany, as-

signor to Siemens Wernerwerk, many & Halske Aktiengesellschaft, Siemensstadt, near Berlin, Gier-vl In Germany March 20,y 1937 1 Application February 24, 193s, serial Na. `192,198

9 claims. Y (o1. 17e-.27)

The invention relates toa circuit arrangement for setting up the variously rated calls in automatic telephone systems and in particular .to

such arrangements in 'Whichwhen setting up a -highly rated call the wanted lslvlbscribers line is immediately blocked prep'aratorilyl in the event completed after a certain time.

In addition to l arrangements in which the called subscriber is no longer able to establish or to receive less expensive calls in the period between the blocking of his line and the nal estab- -lishment ofthe highly rated call, there are also arrangements known in which the called subscriber is still able Vvat least to set upoutgoing calls. These arrangements require a considerable amount oi switching means, because the switching means provided for vthis purpose .are associated with subscribers lines.

The invention iscto avoid this objection. This is achieved in that a preselecting device is associated Ywith a connecting connecting path and is at the disposal of subscribers who are preparatorily blocked on the establishment of a highly rated call, for the purcalls.

'and 2, with Fig. 1 placed to une ieri of Fig. 2',

represent an embodiment of the'invention.- A'

of the establishlocal call and description will first be given ment of an inexpensive, i. e., a

then of the establishment yof a more highlyrated,

Circuitidetails which are of' i. e., a trunk call. no importance for the understanding ofthe invention are not shown` A local call passes in the normal way, first over the preselecting device of thefcalling subthe local group selector IGW, a second group selector ZGW and a final selector OFLW tothe wanted subscriber indicated by Tn.-

The final selector OFLW is thus adapted for the establishment both of local and trunkcalls.

Trunk calls pass from the trunk operators position FPL over a trunk preselector FVW,` 'a

' trunk group selector FGW, a trunk exchange repeater FU@ which is multipledl to the local selector !GW, the second group-selector ZGW and the trunk final selector OFLW to the wanted subscriber Tn. l

In the oase of a ciated with the calling subscriber is set on a free first group selector lGW in the known way after v the calling subscriber has taken up his receiver.

After the local group selector lGW has been seized the feeding bridge relay B1' energizes over v have no bearinglon fore not indicated.

in particular "of the second group selector, off-normal ybrings the switch device disposed in theA local call the preselector assothe closed subscribers loop. The group selector. is set up by the'rst impulsetrain and searches for a second group selector. When this has been found the seizing relay Cl of the second group `selector ZGWenergizes over the testing relay of the group selector lGfW4 (not shown) 'l andthe testing wiperv of -the selector. Thereupon the second group selector 2GW isset by the next` impulse train. This also hunts freely this time `for a free final selector. The switching operations for the setting ofthe tw'o group 4selectors the invention and are theren When a free nal selector has been found the testing relay of the selector GW and the seizing relay of the nal selector OFLW energizes in the following circuit: earth, the windings of the testingrelay PI, the wiper c contact 22k, winding II ofjrelay C2, battery and earth. The testing relay PI of the second group selectorv to rest inthe guards the seized line against further seizure and nally switches through the speaking leads. The seizing relay C2 in the final selector connects its high resistance winding I in the testingcircuit over Contact ZlcZ. Through the closing of contacts 3802 and prepared. Av circuit for the control relay U2 is prepared by the closing of contact 4002.

The impulse trains for setting the final selector on the wanted subscribers line are now trans-l mitted. As the impulses are transmitted the feeding bridge relay Br in the rst group se. lector releases circuit is accordingly completed for the impulse receiving relay A2 in the nal selector: earth, contacts l5br and' lE'c (contact of a seizing relay C which is not shown) wiper a of the rst group selector, Wiper a contact 21102, Winding I of relay of lrelay Y2, battery and earth. final selector energizes mits impulses to the "vertical magnet I-I of the final selector'over'the following circuit: earth, contact M112, windings II'and I of relay V2, contact 421L2, rotary off-normal'contact 431D, vertical magnet H, battery andearth. The switch is raised to the desired level by the impulse train.

A2, winding III Relay A2 inthe known way and i `3902y the'testing circuit is ofthe second group selector,

intermittently andv trans- On the first impulse relay V2 is energized in sel has energized. the

windings II and I ofthe slow operating relay V2, rotary magnet D, battery contacts 4111.2 and 48102, and earth. The rotary Irlagnet'responds` to the impulses and rotates the switch to the desired subscribers line. On the first impulse relay V2 i. on the iirst impulse the following locking circuit is established for relay U2 during the impulse train: earth, contacts 3802, 3902, relay U2, battery impulse train relay A2 first releases permanently. Relay V2 then releases. Duringthe release period of relay U2 the following testing circuit is established: earth, contacts 3302, 3202, 53112 and 52u2, the windings II and I of the testing relay P2, wiper c of the final selector, the testing wiper of the called subscribers preselector in the zero position, the testing relay of the calling subscribers preselector, battery and earth. This testing circuit is only completed if, as has been assumed, the calling subscriber is free.

If the called subscriber is not free the testing relay P2 does not energize. The following circuit is completed for transmitting the busy signal: earth, busy signal transformer Bes, rotary OIT-normal contact 52u) (closed on the first rorelay A2, contacts 55y2, The busy signal is transmitted inductively from winding II to winding I of relay A2 and from there is transmitted over the line to the calling subscriber. The calling subscriber must in this case replace his receiver whereupon the switches are'released and he must later attempt once more to set up the call.

When the testing relay P2 in the nal selector l wanted subscribers line being free, the rotary stepping circuit is broken through subscribers line is does energize.

V2 so long as relay U2 battery, ringing the opening of contact 8112. Through the closing of contact 58292 the high resistance winding II of relay P2 is short-circuited andthe seized guarded against further seizure in the known switched through to the subscriber at contacts 65152 and 56202. Through the closing o-f contact 69102 the following circuit is completed for relay has not yet released: earth, interrupter LU, contact 7211.2, winding III of relay V2, contacts mi2, 733/2, 50792, rotary magnet D, battery and earth. The rotary magnet does not energize in this circuit but relay V2 Relay V2 serves as a ring-connecting relay at this stage of the connection. It brings about the transmission .in thisy circuit of the first ringing pulse and applies ringing current to the called subscribers line over: earth, machine RM, contacts 511;2, 555102, wiper a of the final seiector, the bell `circuit at the called subscribers station, wiper 7J of the final selector, contacts 56232, Slg/2 and 327'?, windings I and II of relay Y2 and earth. Winding II of relay Y2 is short-circuited during the now closed for the control relayv way. The speaking leads are U2 energizes and at contact Hu?.

ringing periods over contacts 38c2, 3902 and 49112 so as to prevent the relay being energized by the ringing current. After release of relay U2 the ringing connecting relay V2 is connected to the so-called 5 seconds interrupter over contact 'iiu2 so that ringing called party every 5 seconds.

If the called subscriber takes up his receiver for the ring connectlng relay V2 is opened immediately at contact 73112. Relay Y2`closes its contacts 323/2 v and Slg/2, thereby switching through the speaking leads and by-passing contacts 3572 and 32512. Relay Y2 by closing its ccnruns as follows: earth, thev tact 'Mg/2, temporarily applies metering potential to the b-lead: earth, battery, rotary magnet D, contacts 39122 and `llyZ, choke coil Dr, winding II of relay P2 and the b-lead. v

The two subscribers can now converse together.

Atthe end of the c all the two subscribers replace their receivers. his receiver rst relay A2 releases first in the nal selector. Relay Y2 holds up in the following circuit: earth, windings II and I of relay Y2, resistance W12, contact 29112, winding III of relay PZ, choke coil Dr, contacts 'Mg/2 and 69192, rotary magnet D, battery and earth.

When now the calling subscriber replaces his receiver, the feeding bridge relay Br rst releases and then the seizing relay C of the first group selector. This initiates the release of the iirst group selector and of the preselector. After the release of the seizing relay C in the irst group selector is broken. In the final selector therefore the seizing relay C2 releases. Relay C2 breaks the circuit tact 38c2. Relay P2 releases and thereby breaks locking circuit for relay Y2. The following circuit is completed for the rotary magnet D; earth, contacts liiilc, 44h12, 79c2, 11u12, 48112, rotary magnet D'. battery and earth. lThe rotary magnet energizes and advances the switch one step. On the energizing of the rotary tacts '15d and '18d are closed. In consequence relay U2 energizes: earth contacts 45k, 45112, ltd, winding II of relay U2, battery and earth. Relay breaks the circuit for the rotary magnet. 'Ihe latter releases and in consequence relay U2 releases. Now, however, the circuit for the rotary magnet is completed again over Contact Huil. The magnet therefore energizes once more and the switch executes a further step. This inter-action con- If the called party puts upv for the testing relay P2 at conby the impulse train and found a free line relay FI tact ns1', ringing key i group selector.

tinues until the switch reaches the rest position where the off-normal contact 45k finally breaks the rotary stepping circuit.

*The establishment of a trunk call to subscriber T'proceeds as follows: The trunk operator at thetrunk position FPL inserts the plug ST in the jack KL and selector FVW. This hunts freely for a free trunk preselector FGW. When 4one has been found the trunk operator transmits impulses vby way of her dial switch, of which only the impulse contact nsz' is represented, for setting the trunk group selector. The setting `takes place in the usual wayL' The s tch is raised to a certain level searches for a free line to second group selector 2GW. In the line be- -tween the trunk group selector and the second group selector there is connected a so-called trunk exchange repeater FUe. This serves to transmit to the local and trunk final selector the special switching operations required in trunk working. When the trunk in the trunk exchange repeater energizes over the testing lead as does also the seizing relay CI in the second group selector.

By means of the next impulse train transmitted from the trunk operators position relay Al in the trunk exchange repeater FUe `is energized impulsively over: earth, dial switch con- RT, plug St, jack KL, wiper a of the-trunk preselector and of the trunk group selector, the winding of relay Al, battery and earth. Relay A! transmits impulses by applying earth to the a-lead, over contacts Bal and 80| to the impulse receiving relay in the second After the setting of the second group selector the nal selector OFLW is again seized and is now set in turn and tests on the subscribers line. The seizing and stepping of the switches takes place in the same manner as' inv a local call.

The trunk call differs from the local'call in 'that after the testing relay P2 of the final sevagainst other local or trunk lector is energized pleted for relay Kl of the repeater FUe and forthe following circuit is comrelay J 2 of the final selector OFLW: earth', winding I of relay J2, contacts 80y2, 257'2, 26112, wiper a of the second group selector, contacts ITUI, Zal, Mci, .531, winding I of relay KI, battery and earth. In this circuit relays J2 and Kl energize. Relay J Z- in the nal selector now locks up in the following circuit: earth, contacts 2002, 2N2, winding II of relay J2, battery and earth. By opening its contact 2572, relay J2 disconnects its winding I from the a-lead. Relay J2 moreover opens'its contacts 327'2 and 359'2 and closes its contacts 3372 and 347'2. Connection between the trunk operators `position and thel called subscribers line`is thus broken and at the same time a connecting path is established to call finder ASZ over the leads a2, b2. By opening its contact 'mi2 relay J2 breaks the circuit for winding III of the ring connecting relay V2. The subscriberisthusnot automatically called in trunk Working. i

Ii subscriber Tn whose line is now guarded calls through the high resistance winding II of Vthe testing relay P2 being short circuited, now wishes to set up a further local call the calling relay Tas of the call finder AS2 is energized over the closed subscribers loop as soon as he takes up his receiver; earth, lead b2, contacts 3352, 31112 and 66122, wper'b of the nal selector, contacts 65122, 68272,

thereby seizes a free trunk pre call `finder AS2.

, group selectors Naturally in place of the call-finder A52 a pre-r vt2/b2 as indicated in dotted lines.

group selector hasv eyz, 341'2, iead dz,

in the known manner and sets itself on the call- When this has occurred relay Tac energizes over the winding IIv of the call-finding testing circuit. The connection is thus switched through to the group selector connected to the The subscriber Tfn is now able to set up a call by means of his dial switch over this group selector which is multipled to other of the local exchange.

selector VW?. can be arranged inlthe branch line when the` subscriber Tn takes up his receiver the calling relay Ris energized and starts up the preselector in the known way.

In the trunk exchange repeater FUe relay K! was energized over its winding I as already mentioned; Relay Kl locks up in the following circuit: earth, contacts IZCI, |3761, winding II of relay KI, battery and earth. Winding I of relay Kl .is disconnected from the a-lead at the same' time through the opening of contact lcl and reu lay Sl is connectedto the a-lead by contact 376i. When the trunk operator finally wishes to set up the trunk callI she first operates the key ATi Vat the trunk operators position. This energizes relay Bl in the trunk exchange repeater: earth, battery, key AT, plug St, jack KL, b-wiper of the trunk preselector, and earth. Relay BI the second group selector, contact 29a2, resisltance Wi2, windings I and l1 of relay Y2, battery and earth. Relay Y2 energizes and by opening breaks the connecting path between the subscriber and the branch line' A local call over this path will thus be contacts 3iy2 and 361/2 (z2/b2. disconnected and at path between and the line of subscriber TrL is tacts 361/2 and 312112. The operator at the trunk position then operates the ringing` key RT and the same time a connecting this transmits ringing current directly to thev local and trunk final seiector s'cribers line free. Thelcase in which the wanted subscribers line is not free but the local and trunk final selector is engaged at the moment of testing will now ybe considered. The testing relay P2 cannot energize in this case and the operator receives the busy signal just as' a subscriber does inlocal calls.

The trunk operator, however, has the facility for connecting to the line and knocking down a low value local call. lShe will normally use only this facility directly before finally completing the trunk call. For this purpose she depresses the connecting key AT at the trunk position. In and the repeater lTfUc and already described. Relay Y2 closes its two contacts38y2 and 393/2; A speaking path is thus established to the wanted subscriber over the condensers C2, this path bridging the opened winding I of relay Tas, battery and earth. The call-finder AS2 starts up.

the winding of relay Bl energizes and closes the followingvcircuit over' relay .Y2 in the final se-` lector, earth, battery, contact 11M, wiper b-'of the trunk op'erators position FPL' set up over con-` it was considered that the selector are energized asY In this case n. mi

` necting earth soon as he replies and contact 2861.2, wiper a of the second contacts 55222 and 66272. 'Ihe trunk operator informs the subscriber ofthe presence of the trunk call and asks him to replace his receiver, indicating that the connection will be disconnected. The operator thereupon depresses the disconnecting key TT in addition to the connecting key. Consequently' in the trunk exchange repea-ter relay Al is energized Bl over `the following circuit: earth, key TI, ringing key Rt, plug St, jack KL, a-wiper of the trunk preselector and the trunk group selector, the winding of the relay Al, repeater and earth. In the battery File earth is applied to the a-lead over contact Qui and thus relay A2 in the inal selector is energized. Thus both relays A2 and Y2 are energized in the final selector, Disconis applied directly to the testing lead over earth, contacts 3802, 5p2, @fly/2, 83,142, 62a?, and the c-wiper of the nal selector. Disconnecting earth is also applied to the a-lead of the nal selector over earth, contacts 380.2, 512,112, 56p?, 6h12, 38g?, and wiper a, of the nal selector. 'I'he disconnection of the local call is now promoted whether the wanted subscriber is the calling or called party in the local call. As soon as the trunk operator releases the disconnecting key testing relay P2 of the local and trunk final selector seized by the trunk operator.` energizes'. The operator then restores the connecting key A'I. Relay Y2 locks up locally after the release of the connecting key,v over its windings I and II, winding III of relay P2, the choke-coil Dr and rotary magnet D. 'Ihe subscriber Tri is now rung from the trunk operators position. As takes down his receiver the feeding bridge relayA? energizes. If, how ever. after the inexpensive call has been disconnected the iinal establishment of the trunk call to the wanted party is delayed and if the wanted subscriber is again to be able to set up outgoing calls the trunk operator releases the whole connection by withdrawing the plug at the trunk position and setting up the connection afresh. In this case the same switching operations are involved as have been described when setting up a trunk call to a free subscriber. The subscribe-rs are thus able to set up calls in the period up to the nal completion of the trunk call over the subscribe1"sequipment associated with the nal selector.

After the called subscriber has replied the following circuit is completed for relay Si in the trunk exchange repeater FUe: earth, battery, winding III of relay Y2,'winding I of relay A2,

group selector, contacts loi, Zal, Ski, winding of relay Si and earth. Relay Sl energizes and transmits a signal to the trunk operato-rs position indicating that the called party replied. l

The disconnection of a trunk call by a second trunk operator is prevented in the following way.

Winding I of relay P2 in the nal selector be short-circuited by the application of direct earth to the c-lead by a second trunk operator but the relay does not release since it is held energized from the trunk exchange repeater over its third winding in the following circuit: earth, contact tici, resistance W2, contact M195, wiper b of the second group selector, winding III of relay P2, the choke-coil Dr, contacts 'Wig/2, G3212, rotary magnet D, battery and earth.

When the called party hangs up the feeding bridge relay A2 rst releases and relay Y2 holds up. The release of relay A2 breaks the circuit for relay Sl in the trunk exchange repeater.

' receiver.

in addition to relay Relay Sl on releasing indicates to the trunk operator that the called party has replaced his The connection What is claimed is: l'. In a telephone system, subscribers lines, a

combination toll and local connector having ac cess to said In a telephone system, subscriberslines, an

2 automatic switch over which said lines are ac-` over saidA switch and for making said one line busy to other preparatory to the a call thereto over said switch, thereafter extending an outgolng one line over said switch before said completion of the call thereto.

3. In a telephone system, a pair of associated automatic switches, subscribers lines accessible to said switches, means for seizing any one of said lines over one of said switches and for making said one line busy to other incoming `calls preparatory to the completion of said call thereto.

4. In a telephone system, subscribers lines, two automatic switches, means ing said incoming and outgoing lines temporarily disconnected, means controlled over said going line.

'7. In a telephone system, subscribers lines, two automatic switches, means for extending: a

connection to one of said switches and for controlling said one switch'thereover to make any desired one of said lines busy to incoming calls without completing said connection to that line, means for completing a connection over said one switch from the desired line to the second automatic switch, means including said last connection and said second switch for then extending an outgoing call from the desired line, and means controlled over said first connection for interrupting said last connection and completing Said first connection to the desired line.

8. In a telephone system, calling stations of two classes, called stations, switching means over Which a call may be extended from a calling station of either class under control of that calling station to any desired called station, other switching means, and means in said rst switching means operated only if the calling station is of a particular class for completing a connection from the desired station to said other switching means before the call to the desired station is completed, and means at the desired station for extending an outgoing call over said other switching means before the incoming call thereto is completed.

9. ln a telephone system, switching means having an incoming line, a primary outgoing line and a secondary outgoing line, said incoming line being normally connected to the primary outgoing line, calling" lines of two classes, called lines, means for extending a connection from a calling line oi either class to said switching means and for controlling said switching means thereover to complete a connection from said primary outgoing line to any desired called line, means in said switching means operated only if the calling line is of a particular class to disconnect the incoming linefrom the primary outgoing line and to connect the outgoing lines together, and means operated thereafter over the incoming line to disconnect the outgoing lines from one another and to reconnect the incoming line to the primary outgoing line.

FRANZ ETZEL. 

